Typically, when an oil or gas well has been drilled, a number of further steps are required to complete the well to ready it for production. A logging operation, a swabbing operation, and an operation involving insertion of pipe or tubing into the well, and finally a perforation step to perforate said tubing, typically are additional steps required to ready a well for production.
The logging step requires the lowering of a logging instrument into the drilled well. The logging instrument is an elongate cylindrical device that is typically lowered from a well-servicing vehicle via an electrically-conductive wireline (referred to in the well completion and servicing industry as an “e-line”) into the drilled well. The logging device emits gamma rays or the like and is used to receive reflected waves from the petroleum formation, such reflected waves indicating physical properties of rock formation in which the well is drilled useful for determining whether further steps, such as whether fractionation of the petrochemical formation in which the well lies, would be needed or beneficial. Information and data from the logging instrument is relayed to the surface of the well via the wireline, and the data is “logged” by means of recording instrumentation, typically situate in the service vehicle at the surface of the well. The logging instrument is thereafter brought to the well surface by the wireline, which is wound on a winch expressly provided on the service vehicle for this purpose.
The step of swabbing a well involves the removal of water which may be in the well, to permit the flow of petroleum from the formation into the well. Such swabbing operation involves the lowering, by means of another wireline, typically a high strength cable, of a plug which has a valve thereon. The plug is lowered in the well, with the water in the well flowing through the valve from the underside of the plug to the upperside of the plug, thereby allowing the plug to settle towards the bottom of the well. Thereafter, the valve closes when the plug is raised. In such manner the raising of the plug allows water above the plug to be removed from the well when the plug is withdrawn, so as to thereby “underbalance” the well and permit its later use in oil or gas recovery. The swabbing operation frequently needs to be carried out a number of times in order that the well be as underbalanced as possible.
After a well is drilled, the well is typically cased with metal tubing or piping so as to prevent inadvertent closure of the well due to shifting or collapse of surrounding strata, and to permit the pumping, in the case of oil, or the pressurized flow of gas, in the case of natural gas, from the well. This step is a further step necessary to complete a well and ready it for production.
In this tubing insertion step, the tubing which is inserted into the well may be continuous tubing, which is typically used in deeper wells (in excess of 1,500-2,000 meters), or in the case of shallow wells, joined pipe is used which provides slightly higher resistance to fluid flow due to the pipe joints, but which is tolerable in shallower wells. Any tubing, regardless of whether continuous or joined pipe, must be perforated at the lowermost extremity of the well, to allow oil or gas to flow into the tubing at the lowermost portion of the well, and thereafter flow up and out of the well via the upper tubing.
Accordingly, the final step in completing a well, typically after logging and swabbing have been carried out, involves the lowering, by means of a conductive wireline, of an explosive charge situated on the lowermost end of the inserted tubing. Such tubing-conveyed charge is then, when substantially all of the tubing been inserted into the well, detonated at the lowermost portion of the well (i.e. the producing portion of the well), to permit gas or oil to flow through into the resulting holes (perforations) in the tubing/casing, and thereby permit the oil or gas, as the case may be, to flow up or be drawn up to the surface of the well via the unperforated tubing now above. This procedure is typically known in the art as TCP (“tubing conveyed perforation”).
Each of the above steps is typically needed to be conducted in order to bring a drilled well into production.
Mobile rigs for the drilling of wells are well known in the art, such as those disclosed in U.S. Pat. Nos. 2,847,098, 3,109,523, 3,670,831, 3,734,210, 3,994,350, 4,371,046, 4,478,291, 5,094,302 and 5,794,723.
Typically, these prior art drilling rigs are relatively large and heavy, particularly where they are adapted for drilling deeper wells (i.e. wells of more than 1500 to 3000 m in depth).
In the prior art, due to the size and complexity of the above prior art drilling rigs, these units are usually only adapted for the drilling of the well. Lighter, less complex, “rigless” well servicing equipment, which cannot drill but which can carry out one or more steps in the completing of the well, such as the logging and/or swabbing operations, are typically employed for these purposes.
One such example of a prior art “rigless” well service vehicle is the “first generation” mobile servicing vehicle manufactured by Big Guns Perforating and Logging Inc. of Calgary, Alberta, Canada, who is also the assignee of this invention described later herein. Such mobile vehicle essentially consists of a double-axle vehicle, the rear bed thereof having a chain-driven winch having a 9/16 inch cable wound thereon for carrying out swabbing operations, and a further drum having a 5/16 inch conductive wireline wound thereon, used for lowering a logging instrument for logging operations. Such vehicle further carried on the bed thereof computerized equipment for “logging” and analyzing the data received from the logging instrument via the 5/16 inch conductive wireline.
This prior art vehicle, while useful, was recognized as being more practical if it could further carry out TCP (tubing conveyed perforation), so that the drilling vehicle which possessed a rig or derrick to permit drilling as well as insertion of tubing into the well would not need to be manoeuvred back over the well to insert the tubing after the logging operations had been done by the service vehicle. In other words, it was recognized that it would be more economical if the Big Guns service vehicle could conduct all of the steps of logging, swabbing, tubing insertion and perforation, so that immediately after drilling the well the drilling rig could permanently depart from the well site to other locations where its valuable services are needed, and leave the task of completion of the well to a service vehicle.
Accordingly, to this end, a mast was further added to the first generation service vehicle made by Big Guns Perforating and Logging Inc., which, by having a mast of at least 30 feet in height, could permit the insertion of 30 foot lengths of jointed pipe into the well to complete TCP. These “second generation” service vehicles then properly became a service rig, in that they then possessed a mast, pivotably coupled to the bed of the vehicle, which could be raised by hydraulic pistons to a substantially vertical or slightly over-vertical position. To stabilize the mast/derrick when in a raised position, such vehicles had manual telescoping stabilizing jacks proximate each of the left, right, front, and back corners of such vehicle, to prevent tipping.
Disadvantageously, however, such “second generation” service rig vehicles needed at least one additional service vehicle having auxiliary equipment such as hydraulic power tongs for the power handling and threading of jointed pipe during the TCP operation. This auxiliary equipment was typically supplied by another service vehicle having such equipment on the rear bed thereof, which provided such function when it likewise was backed up to the well, typically opposite the service rig vehicle, so that workers could utilize the service rig to hold the pipe, and the hydraulic power tongs on the additional service vehicles to thread the joined pipe together for insertion into the well.
As an attempt to design a vehicle which could provide a number of well completion steps, U.S. Pat. No. 6,003,598 teaches a mobile vehicle/carrier 22 having a collapsible mast or derrick 40 which may be hydraulically raised and lowered by means of hydraulic pistons 52. A winch 46 and cable is provided proximate the crown of the derrick 40 for performing functions such as manipulating joined pipe segments if required. A further wireline winch assembly 100 and a drum 102 having a conductive wireline wound thereon allows a logging instrument to be lowered into the well to permit logging and vertical wells.
The vehicle/carrier 22 disclosed in U.S. Pat. No. 6,003,598 possessed stabilizers 32 at each corner, incorporating a vertically extendible hydraulic jack or lifter 34 for engaging the ground 21, to level the rig as desired during operation, thereby removing some or all of the rig's weight from the front and/or rear axles 26,28. A platform 47 was further provided, movable from a retracted position to an operable position by a fastline winch 49 situate proximate the crown of the derrick 40. Notably, platform 47 was permanently affixed to the derrick 40 (ref. FIG. 5) at a fixed height, and travelled with the vehicle 22.
Importantly, vehicle 22 of U.S. Pat. No. 6,0003,598 was adapted for injecting continuous tubing (CT). As such, it possessed a large removable reel 82, part of a cartridge assembly 80, on which CT was wound. An injector 70, slidable on the derrick 40 by means of winch 46, was provided, for injecting the continuous tubing in the well, was also necessary.
While U.S. Pat. No. 6,003,598 discloses that it may be used for manipulating joined pipe (as opposed to CT) if need be, and indeed discloses winch 46 for such purpose, disadvantageously vehicle 22 of U.S. Pat. No. 6,003,598 clearly is poorly suited to insertion of jointed pipe. In particular, such vehicle 22 for effective use in inserted jointed (as opposed to continuous pipe) required another service vehicle having power tongs to mechanically join pipe segments together, as it clearly lacked any such equipment. In particular, for shallower wells, where jointed pipe instead of CT is typically used, to carry out manipulation of jointed pipe would require disengagement of winch 46 with injector 70, as injector 70 was not needed, in order to allow derrick-mounted winch 46 to handle jointed pipe. However, all that winch 46 of U.S. Pat. No. 6,003,598 can do is raise and lower jointed tubing—no power mechanism other than winch 46 is disclosed in U.S. Pat. No. 6,003,598 to handle jointed pipe, nor could the derrick 40, due to the provision of slidable injector 70 on derrick 40, be adapted to provide such power tongs, as they would plainly interfere with the injector 70. Particularly, while U.S. Pat. No. 6,003,598 discloses that such carrier/vehicle 22 may also be used to insert jointed pipe into a well, derrick 40 with its sliding injector 70 clearly lacked the ability to provide upwardly and downwardly moveable power tools to allow power manipulation of jointed pipe, as the injector 70 would necessarily Interfere with such devices. At least one other service vehicle would be necessary to provide such capability.
Accordingly, the ability to insert jointed pipe in an efficient manner was not, nor capable of being, provided by vehicle 22 of U.S. Pat. No. 6,003,598. Accordingly, vehicle/carrier 22 of U.S. Pat. No. 6,003,598 suffered from the similar shortcoming of the second generation Big Guns vehicle, namely the need for other service vehicles having additional equipment to be present.
In addition, due to the provision of a large cartridge assembly 80 for CT injection and a sliding injector 70 on vehicle 22 of U.S. Pat. No. 6,003,598, as well as a platform 47 which was permanently mounted on vehicle/carrier 22 and transported with such vehicle 22, vehicle 22 was necessarily large and cumbersome.
Accordingly, there exists a real need in the industry for a single, multi-function well servicing vehicle for shallow wells, capable to not only conducting logging and swabbing operations, but also effectively and efficiently being able to insert joined pipe into the well. Also necessary is the ability to carry out tubing conveyed perforation, so as to be able to complete a pre-drilled well and ready it for production without the need for any other well servicing vehicles.